Development of a Portable Work Zone
Traffic Safety Information System
using DSRC Based V2I and V2V Communication
M Imran Hayee, Ph. D.
ECE Department, University of Minnesota Duluth
Department of Electrical and Computer Engineering
Outline
• What has been accomplished?
• Phase I
• Phase II
• What is currently being accomplished?
• Phase III
• What could be possible next phase?
Department of Electrical and Computer Engineering
What Has Been Done? – Phase 1
Year: 2008 - 2009
DSRC
RSU or OBU
DSRC-OBU
CID
BT enabled
Cell Phone
MNDOT
Infrastructure
1.
2.
This system was developed and demonstrated in the field
Currently the Bluetooth enabled cell phone gets text messages
Department of Electrical and Computer Engineering
What Has Been Done? – Phase 2
Portable DSRC Based V2I Information System
Year: 2009 - 2010
Distance to SoC
Start of
Congestion
(varying)
Vehicle passing End of
Through
Congestion
congested area
Vehicle approaching
Congested area
Work Zone
DSRC-OBU
DSRC-OBU
DSRC-RSU
SoC location and TT Broadcast from RSU
1.
2.
3.
4.
Two way DSRC communication to
acquire safety and traffic data
It was developed and successfully demonstrated in the field.
Can acquire in real time, important travel information e.g., TT and SoC location
Can communicate to the driver, both TT and distance to the SoC location
Uses BT enabled cell phone text messaging as user interface for the driver
Department of Electrical and Computer Engineering
System Setup
End of Congestion: Known
Start of RSU
Monitoring Range
Desired
Location
End of RSU
Monitoring Range
Start of Congestion: Unknown
Work Zone Lane
RSU
•
•
•
Coverage range of RSU
RSU is placed such that the RSU monitoring range aligns with the end of the congestion.
At periodic intervals, a single OBU participation is requested by the RSU to monitor a
vehicle’s speed and position through a congestion area.
RSU sends traffic alert message to OBUs indicating travel time through monitoring area.
Department of Electrical and Computer Engineering
DSRC Communication Protocol
RSU
OBU
INVITE
RSU
OBU
BROADCAST
ACCEPT
CHOSEN
NOTIFY
•
•
•
•
RSU initiates the communication by sending an INVITE message requesting OBU
participation.
Each OBU receiving the INVITE message screens itself using the information in INVITE
message and if passes the screening, it will respond with the ACCEPT message.
The RSU will screen the incoming ACCEPT messages to ensure that the OBU is on the
monitored road, and sends CHOSEN message to the originating OBU of the first ACCEPT
message to pass.
OBU periodically communicates NOTIFY messages until EoC point approaching is detected,
then RSU is alerted before OBU ceases to send further NOTIFY messages.
Department of Electrical and Computer Engineering
Field Testing
Frequency
(b)
Culmantive Precentage
70
120
60
100
Frequency
50
X
80
40
60
30
40
20
20
10
0
0
1
•
•
Culmanative Precentage
(a)
2
3
4
Location Error (m)
5
6
The location accuracy of the GPS is the most important factor when determining the possible
error in measurements.
The location accuracy error in turn causes errors in distance and direction measurements.
Department of Electrical and Computer Engineering
GPS Distance Accuracy
Urban Area – accuracy is +/- 3 m
5m - UMD
15m - UMD
10m - UMD
30
30
25
25
20
20
15
15
10
10
5
5
0
0
18
16
14
12
10
8
6
4
2
3
4
5
6
7
8
0
7
8
9
10
11
12
12
13
14
15
16
17
18
19
Rural Area – accuracy is +/- 2 m
5m - Mora, MN
10m - Mora, MN
30
15m - Mora, MN
40
35
35
25
30
30
20
25
25
20
15
20
15
15
10
10
10
5
5
5
0
0
3
4
5
6
7
0
8
9
10
11
12
13
14
15
16
17
9
Department of Electrical and Computer Engineering
GPS Direction Accuracy
A
A
B
B
5m
Direction Error 30 degrees
10 m
15 m
14 degrees
10 degrees
Direction Error decreases if distance is increased
10
Department of Electrical and Computer Engineering
Field Demonstration
Start of Congestion: Unknown
Start of RSU
Monitoring Range
End of Congestion: Known
End of RSU
Monitoring Range
RSU
•
•
The field demonstration site was chosen at Rice Lake Rd, Duluth MN with the
focus on providing a clear line of sight between RSU and the OBU.
The RSU is placed near the congestion end due to reduced range on one side due to
signal blocking by back of the vehicle.
Department of Electrical and Computer Engineering
Traffic Safety Parameters
25
25
Congestion Length
(a)
20
40 MPH mark
15
Speed (m/s)
Speed (m/s)
20
10
20 MPH mark
5
SoC
EoC
0
150
300
450
Distance (m)
•
600
750
40 MPH mark
15
10
20 MPH mark
5
0
0
•
TT
(b)
SoC
0
EoC
30
60
90
120 150 180
Time (sec)
The traffic parameters - Start of Congestion location and the Travel Time are
calculated by RSU
The update frequency is determined based upon the TT. If TT is larger, multiple
vehicles are chosen at the same time to be monitored.
Department of Electrical and Computer Engineering
Field Demonstration Results
(a)
20
15
10
10
0
0
400
Distance (m)
600
800
SoC
15
5
200
(b)
20
5
0
•
25
SoC
Speed (m/s)
Speed (m/s)
25
0
200
400
600
800
Distance (m)
Congestion scenarios of varying start of congestion location and congestion depth
were tested for different vehicle speeds.
Department of Electrical and Computer Engineering
What is Being Done? – Phase 3
The Range of the current system is limited to 1 km because of the DSRC antenna range.
However the calculated traffic parameters of the system are more useful to the driver if its
received earlier. Also congestion or a work zone area may exceed 1 km requiring more
range to be covered.
In the current phase 3 (2010-2011), the objective is to utilize the V2V DSRC communication
to the developed Portable Work-Zone Safety Message Relay System to
1. Increasing the Message Broadcast Range
2. Increasing the Work-zone Coverage Length
Department of Electrical and Computer Engineering
Increasing the Message Broadcast Range
1 km
Portable
DSRC RSU
1 km
1 km
V2I
V2I
V2V
V2V
We intend to increase the message broadcast range using V2V-assisted DSRC
communication. To increase the message broadcast range, we propose to use the selected
vehicles on the road approaching to work zone to help relay the traffic safety messages
backwards to the vehicles following them, to achieve much longer message broadcast
range without having an extensive DSRC roadside infrastructure.
Department of Electrical and Computer Engineering
Increasing the Work-zone Coverage Length
1 km
Portable
DSRC RSU
1 km
V2I
1 km
V2I
V2V
V2V
V2V
Similarly, we propose to use V2V-assisted communication to cover much longer work
zones beyond the access range of one portable roadside DSRC unit. This will be
accomplished with the help of selected vehicles present on the work zone well out of
reach of the portable roadside DSCR unit to help facilitate V2V-assisted V2I traffic
data exchange.
Department of Electrical and Computer Engineering
Progress of the Current Phase
1.
Increasing the Message Broadcast Range
1. V2V communication.
2. Develop method for distance measurement adjustment vs. displacement.
3. Develop and test the V2V communication protocol for extended range.
4. Demonstrate the algorithm for distance adjustment in V2V environment
2. Increasing the Work-zone Coverage Length
1. Develop protocols for handling messages from other OBU’s in the OBU program.
2. Develop protocols for extending and contracting the monitored area.
3. Demonstrate the system in field.
Note: The green tasks have been done and the blue tasks are being worked on.
The project is expected to finish in time (during June/July 2010 time frame)
Department of Electrical and Computer Engineering
Curve Fitting
Start of Congestion
14
Measured distance
Actual Distance (km)
12
Curved Road
10
8
Straight Road
6
4
2
0
0
2
4
6
8
10
Straight Line Distance (km)
The road curvature is statistically modeled by a polynomial fit, parameters of which
can be communicated to the OBU so that it can adjust the measured displacement.
Department of Electrical and Computer Engineering
12
What Next?
1 km
Current: V2V assisted V2I
Portable
DSRC RSU
1 km
V2I
1 km
V2I
V2V
V2V
1 km
Portable
DSRC RSU
V2V
Pure V2V ?
1 km
V2I
1 km
V2I
V2V
V2V
V2V
19
Department of Electrical and Computer Engineering